Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
2002-07-03
2004-04-06
Vo, Anh T. N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
C347S086000
Reexamination Certificate
active
06715865
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method of packing a liquid jet recording head to be used for printing by ejecting liquid droplets from ejection orifices onto a printing medium. The present invention also relates to a liquid jet recording head and a liquid jet recording apparatus equipped with such a liquid jet recording head.
2. Related Background Art
Conventional liquid jet recording apparatus comprise a carriage adapted to reciprocate in a direction almost perpendicular to the moving direction of the recording medium, and a liquid jet recording head is mounted on the carriage.
The liquid jet recording head comprises as principal components thereof a liquid jet section for ejecting liquid from its ejection orifices onto a recording medium for the purpose of recording and a liquid storage chamber containing liquid to be supplied to the liquid jet section. There are exemplified liquid jet recording heads that typically comprise a liquid storage section as an integral part thereof and can be replaced for the liquid jet recording apparatus on which they are mounted.
Such liquid jet recording heads are not adapted to be refilled with liquid when the liquid contained therein is used up. In other words, when the liquid initially contained in a liquid jet recording head is totally consumed, the latter is disposed as waste and a new one is mounted on the scanning carriage. With such an arrangement, the running cost of the liquid jet recording apparatus will be high particularly when the liquid jet recording head is replaced frequently.
On the other hand, there are exemplified liquid jet recording heads of the type designed to reduce the running cost and provided with a separate liquid storage section so that only the latter may be replaced when all the liquid contained in the section is consumed. There are also known liquid jet recording heads of the type provided with an external liquid storage chamber from which liquid is supplied to the liquid jet recording head. Liquid jet recording heads of these types are also designed to reduce the running cost.
In short, known liquid jet recording heads are classified into (1) those that are provided with a liquid storage chamber arranged in the inside of the liquid jet recording head, (2) those that are provided with a replaceable liquid storage chamber and (3) those that are supplied with liquid from a remote liquid storage chamber connected thereto typically by means of a pipe.
Regardless of the type of liquid jet recording heads, however, the internal pressure of the head is normally held to a level lower than the atmospheric pressure or to a negative pressure level relative to the outside of the head in order to prevent liquid from leaking out of the liquid jet recording head.
Now, some of the characteristic aspects of the negative pressure generating means of the liquid supply system of a liquid jet recording head of each of the above identified types will be discussed below.
In the case of a liquid jet recording head provided with a liquid storage chamber arranged in the inside thereof, the liquid storage chamber is normally equipped with a negative pressure generating means for maintaining the negative pressure in the liquid storage chamber. The negative pressure generating means may be a liquid absorbing means (liquid absorption system), a mechanical means or some other means.
A liquid absorption means is typically designed to utilize the capillary force of a porous liquid absorbing material such as urethane in order to maintain the negative pressure in the liquid storage chamber and, at the same time, retain the liquid therein. A mechanical means is typically adapted to utilize the resilient force of an elastic body so as to contract a flexible wall, thereby maintaining the negative pressure in the liquid storage chamber.
Now, a liquid jet recording head provided with a replaceable liquid storage chamber will be described below. A liquid absorption system is typically employed as negative pressure generating means in a liquid jet recording head provided with a replaceable liquid storage chamber. More specifically, such a liquid absorption system is adapted to prevent liquid in the storage chamber from dropping through the connection port of the liquid storage chamber by means of the liquid retaining force of the porous liquid absorption member thereof.
Next, a liquid jet recording head adapted to be supplied with liquid from an external liquid storage chamber will be discussed below. A liquid jet recording head of this type may be provided with a negative pressure generating means of the liquid absorption type or of the mechanical type or may be adapted to maintain the negative pressure in the liquid jet recording head by means of the water head difference that is produced as a result of the fact that the liquid level in the external liquid storage chamber is lower than the level of the plane of the ejection orifices of the liquid jet recording head.
A liquid jet recording head may be made to eject liquid droplets from its ejection orifices by utilizing thermal energy generated by electro-thermal transducers or by deflecting liquid droplets by means of a pair of electrodes. Liquid jet recording heads adapted to eject liquid droplets by utilizing thermal energy are commercially available and very popular because of the advantages thereof including that liquid ejection orifices for forming liquid droplets that are to be ejected for the purpose of recording can be arranged densely and high resolution images can be formed by this arrangement as well as that the entire head can be made compact with ease.
In ink-jet recording head adapted to eject recording liquid by utilizing thermal energy comprises ejection orifices for ejecting liquid, liquid flow paths communicating to the respective ejection orifices and electro-thermal transducers arranged vis-à-vis the respective flow paths so that it applies ejection energy (e.g., thermal energy for causing liquid to give rise to film boiling) coming from the electro-thermal transducers to the liquid flowing through the liquid flow paths and ejects droplets of liquid through the ejection orifices for a recording operation.
In recent years, ink-jet recording apparatus of various types have been developed and become very popular. Additionally, the recording capacity of such apparatus has been increased so that the consumption of recording liquid is also increasing. As a result, the demand for ink-jet recording apparatus having a large liquid storage capacity has been rising rapidly.
However, liquid jet ejection heads of the above described types (1) through (3), those of the type (1) having a liquid storage chamber as an integral component thereof and those of the type (2) provided with a replaceable liquid storage chamber are accompanied by the problem of a limited capacity of the liquid storage chamber. In other words, the liquid storage chamber or the liquid jet recording head itself has to be replaced frequently to impose a cumbersome replacing operation to the operator (user) particularly when recording liquid is consumed at a high rate. Furthermore, the cost of such consumables is far from negligible.
If, on the other hand, the capacity of the liquid storage chamber is raised, the total weight of the liquid jet recording head increases to raise the inertial force that is produced in the scanning operation of the carriage. Then, there arises a problem that the carriage may not be stable nor reliable for scanning operations to consequently degrade the quality of recording.
Additionally, if the capacity of the liquid storage chamber that is mounted on the carriage is raised, the entire liquid jet recording apparatus may become bulky.
Contrary to liquid jet ejection heads of the above two types, those of the type (3) provided with an external liquid chamber, from which liquid is supplied, are advantageous in that the liquid storage chamber can be placed relatively freely and the recording apparatus is free from becoming bulky if the capacity of th
Koizumi Yutaka
Umeyama Mikiya
Yamaguchi Yukuo
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Vo Anh T. N.
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